Implantable medical devices including those that are positioned on the exterior of a body of a patient as well as those that are positioned subcutaneously or deeper typically utilize an on-board battery that allows the patient to be untethered to a power source. The patient maintains mobility while the implantable medical device performs a particular medical task by operating on power from the battery. For instance, the implantable medical device may provide stimulation therapy for neurological or cardiac conditions, may provide drug delivery for various conditions such as pain management, and/or may provide physiological monitoring.
While the on-board battery may power the medical device for a relatively long period of time, the on-board battery will eventually be depleted. Prior to rechargeable medical systems, the implantable medical device would be replaced once the battery became depleted. With rechargeable medical systems, an external device provides recharge energy over a proximity coupling, which is typically inductive, to the implantable medical device. This recharge energy restores the on-board battery to a satisfactory level for continued operation of the medical device.
During a recharge session, the external device in control of the recharge energy and the implantable medical device to be recharged exchange telemetry communications related to the recharge process. Recharge information such as battery status, coupling efficiency and the like may be transferred in this manner so that the external device can properly control delivery of the recharge energy as well as instruct a user. Conventionally, the two devices exchange telemetry communications over a proximity coupling. However, this proximity coupling is also being used to transfer the recharge energy, and in some cases recharging may stop while the telemetry communications are conducted over the proximity coupling. This increases the amount of time needed to complete the recharge session.